1. Field of the Invention
The present invention relates to a rubber composition having an excellent abrasion resistance and an excellent low heat generation property.
2. Description of the Background
Heretofore, in order to obtain a low heat generation property in a rubber composition, certain techniques have been employed, such as (1) using a low reinforcing carbon black having a low specific surface area as the carbon black, and (2) decreasing the compounding ratio of the carbon black.
On the other hand, in order to improve the abrasion resistance, other techniques have been employed, such as (1) using a high reinforcing carbon black having a high specific surface area as the carbon black, and (2) increasing the compounding ratio of the carbon black. Since these techniques are contradictory to one another, there has been a problem that the abrasion resistance is lowered when the low heat generation property is retained, and the low heat generation property is deteriorated when the abrasion resistance is improved.
As mentioned above, it has not been possible to make the two characteristics compatible by conventional means, and it has been desired to develop a rubber composition possessing both characteristics.
Japanese Patent Application Laid-Open No. Hei 3-50249 discloses a rubber composition having both high resilience and abrasion resistance which comprises 100 parts by weight of a rubber component and 30-100 parts by weight of carbon black belonging to a hard system region in which the nitrogen adsorption specific surface area (N.sub.2 SA) is 58-139 m.sup.2 /g and the DBP oil absorption amount is 90-150 ml/100 g and having a selective characteristic that the gap size among particles D.sub.p (nm) determined by a mercury porosimetry is a value calculated by the following formula, or more. EQU {-0.22.times.(N.sub.2 SA)+60.8 } (Formula 2)
However, this rubber composition is by no means satisfactory.